Bronchial hyperreactivity

Bronchial Hyperreactivity (BHR) refers to the phenomenon where the bronchi in the lungs react to various stimuli more strongly than is normal. This condition is closely associated with asthma, but it can also be seen in individuals without asthma. BHR is characterized by excessive contraction of the bronchial muscles, leading to narrowing of the airways, which can cause symptoms such as wheezing, coughing, shortness of breath, and chest tightness.

Causes and Risk Factors

The exact cause of bronchial hyperreactivity is not fully understood, but it is believed to involve a combination of genetic and environmental factors. Risk factors for developing BHR include a family history of asthma or allergies, frequent respiratory infections during childhood, exposure to airborne irritants (such as tobacco smoke, pollution, and occupational chemicals), and living in an area with high allergen levels.

Pathophysiology

Bronchial hyperreactivity involves an exaggerated response of the airways to stimuli. This can be triggered by allergens, cold air, exercise, infections, and stress. The underlying mechanism involves inflammation and swelling of the airway walls, increased mucus production, and bronchoconstriction (tightening of the muscles around the airways). These changes result in narrowed airways, making it difficult for air to flow in and out of the lungs.

Diagnosis

Diagnosis of bronchial hyperreactivity typically involves a medical history review and physical examination, along with lung function tests. The most common test used to assess BHR is the methacholine challenge test. This test involves inhaling increasing concentrations of methacholine, a substance known to cause bronchoconstriction, and measuring lung function using spirometry. A significant decrease in lung function following methacholine inhalation indicates the presence of BHR.

Treatment

Treatment for bronchial hyperreactivity focuses on managing symptoms and reducing exposure to known triggers. Medications used to treat BHR include inhaled corticosteroids to reduce inflammation, bronchodilators to relax the muscles around the airways, and leukotriene modifiers to decrease airway constriction. Avoiding triggers, such as allergens and irritants, is also an important part of managing BHR.

Prevention

Preventive measures for bronchial hyperreactivity include avoiding exposure to known triggers, such as tobacco smoke, pollution, and allergens. Regular use of prescribed medications can also help prevent symptoms and exacerbations. Vaccinations, such as the flu vaccine, are recommended to reduce the risk of respiratory infections that can worsen BHR.

See Also

• Asthma
• Allergies
• Chronic Obstructive Pulmonary Disease (COPD)
• Respiratory Therapy